This invention relates to a rotary agitator for insertion into a large container such as a drum, in combination with a suction tube for removing liquid from the container.
Mechanical agitators and liquid pumps for agitating and removing liquid from large containers are known in the art, because there has long been a problem with storing liquids over indeterminate times in large containers while at the same time maintaining the liquid in condition for immediate use. Many liquids comprise mixtures of various components which may tend to settle out or separate over extended storage periods, particularly when stored in large drums. It, therefore, has become necessary to continuously agitate the liquid in order to maintain uniform consistency prior to use. The liquid may then be removed by pumping at any time for delivery to a point of application, and the user can be assured that the component consistency of the liquid is uniform.
Typical large containers have a bung hole opening for obtaining access to the interior liquid without entirely removing the cover. A threadable plug is usually inserted into the bung hole opening, and the plug may be removed for access to the liquid without unduly exposing the interior liquid to the outside air. One of the problems in preserving this limited access to the interior of the drum is that the agitator and the pumping mechanism must both be insertable through the bung hole opening.
This problem has been solved in U.S. Pat. No. 5,193,908, issued Mar. 16, 1993, by providing a rotary agitator having an elongated rotatable tube with a helical agitator flight affixed to the outside of the tube. The interior of the tube is hollow, and the lower end of the tube is open to receive liquid from the container. The top end of the tube is closed and adapted for connection to a rotary motor, and a number of ports are provided through the sidewalls of the tube proximate the top end. These ports are in flow communication with an exterior port in the housing of the apparatus, and a suitable pumping device may be connected to the exterior port for providing suction forces to remove liquid from the container via the hollow tube. The housing is threadably secured to the bung hole opening, and an auxiliary air inlet is provided to permit pressure equalization into the container interior as the liquid material is withdrawn. One problem with this construction is that the drive motor rotates the entire tube; and therefore, dynamic liquid seals must be provided between the rotatable tube and the interior housing in order to prevent leakage of the pumped liquid into the interior of the housing, or to prevent air from entering into the liquid flow path within the housing. If air leaks into the liquid flow path, it becomes entrained in the liquid volume flow and is delivered to the point of application. If the applicator is a spray gun or other similar device, the entrained air becomes ejected by the applicator as noticeable "spitting," thereby disturbing the uniform flow rate delivery of the application. This emission can also disturb the uniform application of the liquid to an article when the spray gun applicator is intended for applying a fine, uniform finish to the article.